Kinetic Studies and Predictions for Xylo-Oligosaccharide Production by Acidic Hydrolysis of Xylan with Various Acids

Acidic hydrolysis of xylan for xylooligosaccharides production has already been intensively investigated allowing for its high efficiency and simple manufacturing procedure. However, kinetic and model equations for acidic hydrolysis of xylan are still unsatisfied. In this study, four acids (sulfuric acid, maleic acid, lactic acid and acetic acid) with different pKa values were employed to hydrolyze xylan and the different kinetic models were established by further analyzing the hydrolysis process from the perspective of reaction rate and activation. All results confirmed that the weaker organic acids were more beneficial to the production of xylo-oligosaccharides, allowing a higher generation rate of xylooligosaccharides and a lower xylose rate. Finally, a xylooligosaccharides yield of 47.2% could be achieved by lactic acid hydrolysis with a pKa of 3.86 based on prediction of kinetic models. This study provides a convenient and convincing method for the selection of acids on xylooligosaccharides production from xylan.